Lange Sabine S, Mitchell David L, Vasquez Karen M
Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Smithville, TX 78957, USA.
Proc Natl Acad Sci U S A. 2008 Jul 29;105(30):10320-5. doi: 10.1073/pnas.0803181105. Epub 2008 Jul 23.
High mobility group protein B1 (HMGB1) is a multifunctional protein with roles in chromatin structure, transcriptional regulation, V(D)J recombination, and inflammation. HMGB1 also binds to and bends damaged DNA, but the biological consequence of this interaction is not clearly understood. We have shown previously that HMGB1 binds cooperatively with nucleotide excision repair damage recognition proteins to triplex-directed psoralen DNA interstrand cross-links (ICLs). Thus, we hypothesized that HMGB1 modulates the repair of DNA damage in mammalian cells. We demonstrate here that mammalian cells lacking HMGB1 are hypersensitive to DNA damage induced by psoralen plus UVA irradiation (PUVA) or UVC radiation, showing less survival and increased mutagenesis. In addition, nucleotide excision repair efficiency is significantly decreased in the absence of HMGB1 as assessed by the repair and removal of UVC lesions from genomic DNA. We also explored the role of HMGB1 in chromatin remodeling upon DNA damage. Immunoblotting demonstrated that, in contrast to HMGB1 proficient cells, cells lacking HMGB1 showed no histone acetylation upon DNA damage. Additionally, purified HMGB1 protein enhanced chromatin formation in an in vitro chromatin assembly system. These results reveal a role for HMGB1 in the error-free repair of DNA lesions. Its absence leads to increased mutagenesis, decreased cell survival, and altered chromatin reorganization after DNA damage. Because strategies targeting HMGB1 are currently in development for treatment of sepsis and rheumatoid arthritis, our findings draw attention to potential adverse side effects of anti-HMGB1 therapy in patients with inflammatory diseases.
高迁移率族蛋白B1（HMGB1）是一种多功能蛋白，在染色质结构、转录调控、V（D）J重组和炎症中发挥作用。HMGB1还能结合并使受损DNA弯曲，但其这种相互作用的生物学后果尚不清楚。我们之前已表明，HMGB1与核苷酸切除修复损伤识别蛋白协同结合至三链定向补骨脂素DNA链间交联（ICL）。因此，我们推测HMGB1可调节哺乳动物细胞中DNA损伤的修复。我们在此证明，缺乏HMGB1的哺乳动物细胞对补骨脂素加紫外线A照射（PUVA）或紫外线C辐射诱导的DNA损伤高度敏感，存活率降低且诱变增加。此外，通过从基因组DNA修复和去除紫外线C损伤评估，在缺乏HMGB1时核苷酸切除修复效率显著降低。我们还探讨了HMGB1在DNA损伤时染色质重塑中的作用。免疫印迹表明，与HMGB1功能正常的细胞相比，缺乏HMGB1的细胞在DNA损伤时未出现组蛋白乙酰化。此外，纯化的HMGB1蛋白在体外染色质组装系统中增强了染色质形成。这些结果揭示了HMGB1在DNA损伤的无差错修复中的作用。其缺失导致诱变增加、细胞存活率降低以及DNA损伤后染色质重组改变。由于目前正在开发针对HMGB1的治疗败血症和类风湿性关节炎的策略，我们的发现提请注意抗HMGB1疗法在炎症性疾病患者中可能产生的不良副作用。
